Criminal law is one of the branches of the legal system, distinguished from civil law. In this article, we’ll define the term “criminal law” and explain various facets of it including criminal codes, elements of a crime, types of a crime, and defenses.

Key Takeaways

• Criminal law is a system of laws enacted to punish those who have committed a crime
• A crime is any act or omission that violates the law
• In contrast with criminal law, civil law aims to resolve disputes between private citizens
• The federal government and each state have their own codes of government criminal law, procedure, and sentencing
• There are three elements to a crime that the prosecution in a criminal case must prove beyond a reasonable doubt: actus reus, mens rea, and proximate causation
• There are four types of crimes: felonies, misdemeanors, inchoate offenses, and strict liability offenses 
• Common defenses in criminal cases include failure or proof, self-defense, and necessity among others

What Is Criminal Law?

Criminal law is the branch of the law system that concerns the punishment of people who commit crimes. A crime is defined as any act or omission that violates a law.  

Criminal Law vs. Civil Law

In criminal law, the prosecution involves the government deciding whether to punish an individual for and how to punish an individual for committing a crime. In contrast, civil law is related to solving disputes between private citizens, often relating to money and property. 

Criminal Codes and Procedure

Each state as well as the federal government has its own criminal code designating what is a crime and how to punish it. Title 18 of the U.S. Code with §§ 1 to 2725 codifies the federal criminal law and criminal procedure. It designates various conduct as federal crimes and prescribes a maximum sentence appropriate for individuals convicted of these crimes. These include:

• Arson
• Use of chemical weapons
• Counterfeit and forgery
• Embezzlement
• Espionage
• Genocide
• Kidnapping

Further, the Federal Rules of Criminal Procedure codify the procedures which must take place during the course of a criminal proceeding. 

Note that Congress has limited power to make criminal laws, making state criminal codes much more detailed and complicated than the U.S. Code.

Elements of a Crime

According to the law, every crime has three elements:

1. Actus reus - the conduct or act itself
2. Mens rea - the individual’s mental state at the time of the act
3. Proximate causation - the causation between the act and the effect

In a criminal case, the burden of proof is on the government to establish every element of a crime beyond a reasonable doubt. 

Types of Crimes

There are four types of crimes:

• Felonies - The most serious type of crime
• Misdemeanors - A less serious type of crime
• Inchoate offenses - A type of crime completed by taking a punishable step toward committing another crime
• Strict liability offenses - Actions considered to be criminal regardless of the person's intentions

Common law, federal law, and state law all classify crimes in different ways. However, there are nine crimes that are usually classified as felonies: 

• Murder
• Robbery
• Manslaughter
• Rape
• Sodomy
• Larceny
• Arson
• Mayhem
• Burglary

Defenses in Criminal Law

The defendant in a criminal prosecution has a number of defenses available to them. Some of the most common are:

• Failure or proof - claiming the prosecution has not proven an element of the offense
• Self-defense - claiming the defendant used force to protect themselves from an attempted injury by another
• Defense of property - claiming the defendant used force to protect their property from a felony occurring within
• Defense of others - claiming the defendant used reasonable force to protect a third party against an assailant who sought to inflict force upon the third party
• Necessity - claims the defendant had to engage in the conduct to avoid a greater harm
• Duress - a partial defense claiming another individual forced the defendant to engage in illegal conduct by force or threat of force
• Insanity - a partial defense claiming that the individual was insane when they committed the crime